package cn.westv.scps.connTools;

import org.springframework.util.Assert;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SecureRandom;
import java.util.zip.CRC32;

/**
 * Created with IntelliJ IDEA.
 * User: HOTLEAVE
 * Date: 13-7-23
 * Time: 上午10:20
 */
public class AESUtil {
    private static final String ALGORITHM = "AES";

    /**
     * 加密字符串
     *
     * @param content  待加密内容
     * @param password 加密密码
     * @return 加密后的内容
     * @throws Exception
     */
    public static byte[] encrypt(String content, String password) throws Exception {
        Assert.notNull(content);
        Assert.notNull(password);

        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, generateKey(password));

        return cipher.doFinal(content.getBytes("UTF-8"));
    }

    /**
     * 解密
     *
     * @param content  加密内容
     * @param password 密码
     * @return 解密后的内容
     * @throws Exception
     */
    public static byte[] decrypt(byte[] content, String password) throws Exception {
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, generateKey(password));

        return cipher.doFinal(content);
    }

    public static short getCRC(String region, int i, byte[] data) {
        CRC32 crc32 = new CRC32();
        if (region != null) {
            for (int j = 0; j < region.length(); j++) {
                char c = region.charAt(j);
                crc32.update(c);
            }
        }
        crc32.update(i);
        crc32.update(i >> 8);
        crc32.update(i >> 16);
        crc32.update(i >> 24);
        for (int k = 0; k < data.length - 2; k++) {
            crc32.update(data[k]);
        }
        return (short) (int) crc32.getValue();
    }

    private static SecretKeySpec generateKey(String password) throws Exception {
        byte[] pwd = password.getBytes("UTF-8");
        KeyGenerator generator = KeyGenerator.getInstance(ALGORITHM);
        SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
        secureRandom.setSeed(pwd);
        generator.init(128, secureRandom);

        SecretKey secretKey = generator.generateKey();
        byte[] enCodeFormat = secretKey.getEncoded();

        return new SecretKeySpec(enCodeFormat, ALGORITHM);
    }

    /**
     * 将二进制转换成16进制
     *
     * @param buf
     */
    public static String parseByte2HexStr(byte[] buf) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < buf.length; i++) {
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

    /**
     * 将16进制转换为二进制
     *
     * @param hexStr
     */
    public static byte[] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1)
            return null;
        byte[] result = new byte[hexStr.length() / 2];
        for (int i = 0; i < hexStr.length() / 2; i++) {
            int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
            int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }

}
